A study of projects in the Design-Build Institute of America’s database concludes that the design-build delivery approach succeeds in bringing projects to completion on time but suggests that half the projects analyzed ran over budget.
There may be a problem with that conclusion, however.
In a statement, DBIA claims that the study results are off the mark because the authors failed to account for owner-initiated scope increases that add to project costs.
The authors never coordinated with DBIA about using the association's database and "if they had," according to DBIA's statement, the authors may have "drawn a different conclusion."
The study, by a team of university researchers in China and Australia, reviewed 418 design-build projects in DBIA's database.
The team took note of start and completion times and cost overrun rates associated with different project types.
The paper is entitled, “Time and Cost Performance of Design-Build Projects.” Published in the February issue of the Journal of Engineering and Construction Management, the study also sorted results based on contract methods and LEED rating levels.
According to a summary of the study on the website of the American Society of Civil Engineers, which publishes the journal, the most commonly used award method is best-value with discussion and the dominant contracting method is lump sum.
'Relatively Good Time Performance'
Overall, the authors write that design-build provides “relatively good time performance, with more than 75% of the projects completed on time or before schedule.”
Half of all the projects ran over budget, however, so the delivery method’s “advantage of cost saving remains uncertain,” the authors write.
But that's not true, says DBIA's executive director, Lisa Washington.
“DBIA’s database of design-build projects is based on information submitted by project teams and owners,” says Washington. “Submitters provide the original contracted cost as well as the final project cost. The database does not include information on owner-directed changes that result in intentional modifications to scope and budget. In the absence of access to this additional information, projects can appear to be over budget, but in fact are not."
Research shows an advantage of design-build as “less cost growth,” which is different than “cost savings,” says Washington.
Contacted via email, one of the study's authors said that he welcomed DBIA's input. "We agree with Lisa's comments," he wrote. "As the paper has been officially published, I don't think we can add the additional information at this stage. However, this journal provides a wonderful platform for discussion between the authors and readers. We encourarge DBIA to submit a discussion to this journal to include that valuable information about the DBIA database" and "we are very glad to offer any help if needed."
Another interesting research paper about design-build appeared in the same journal’s October 2015, issue.
Its authors created a model to see if proactive risk management could ease some of the tension that builds in use of contingency funds on design-build projects. That study is called, “Dynamic Management of Risk Contingency in Complex Design-Build Projects.”
This story was amended April 13 to include more information from the study's author.